Fortified gas marbles are 10 times stronger than regular bubbles

It’s a bubble, but better. Reinforced bubbles called gas marbles are stronger and hold their shape better than their “liquid marble” counterparts or regular soap bubbles – properties that could be useful in areas such as making stronger foams and drug delivery.

Liquid marbles were created for the first time in 2001, when French researchers rolled liquid drops in minuscule hydrophobic particles to create fortified, stable droplets. These are potentially useful for transporting extremely small quantities of liquids and in tiny chemical reactors, which are often used in fuel processing.

The new gas marbles, created by Yousra Timounay at Syracuse University in New York and her colleagues, are similar in concept: they are made of a small amount of gas trapped in a single layer of particles embedded in a liquid film. Basically, they’re millimetres-wide soap bubbles reinforced with a coating of solid particles, like a chocolate sweet covered in sprinkles.

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Unlike regular bubbles, gas marbles can hold their shape even when there’s a pressure differential between the air inside and outside them. “If you take a balloon or a bubble and infuse a gas inside of it, it will deform,” says Timounay. But use pressure to try to inflate or deflate a gas marble and it won’t do so, she says.

Eventually, the gas marbles do rupture and collapse – but they can withstand both positive and negative pressures about 10 times higher than regular bubbles or liquid marbles. “Finding that they’re 10 times stronger than the liquid marbles was really exciting and surprising,” says Timounay.

“The fact that they were stronger I probably couldn’t have guessed,” says Bernard Binks at the University of Hull in the UK. “It was surprising, and a nice result.”

Foams, drug delivery and tracers

Because these strong bubbles can be stacked without losing their shape, they could potentially be used to make lighter, stronger foams for everything from cosmetics to insulation. They could also store valuable gases for drug delivery through the lungs, or imprison those used as tracers to study air or water flows, Timounay says.

More testing is needed before gas marbles will be useful, though. Timounay and her colleagues showed that the bubbles are good at coping with changes in pressure, but it’s not yet clear how long they could last before the liquid layer evaporates and frees the gas, or whether the gas can leak out through the particle layer. Their resistance to squishing and shear forces, under which two parts of the bubble are pushed in different directions, has also not yet been tested.

“I don’t know how robust they will be under those mechanical forces,” says Binks. “Without that information, it’s pretty impossible to guess what applications these will have.”